1. Field of the Invention
The present invention relates to a stable microwave oscillation apparatus.
2. Description of the Related Art
A prior art microwave oscillation apparatus is comprised of a negative resistance element, a microstrip line having an end connected to the negative resistance element and another end connected to a terminating resistor, and a dielectric resonator magnetically connected to the microstrip line, to thereby generate a microwave output having a resonance frequency f.sub.o determined by the microstrip line and the dielectric resonator. In this prior art microwave oscillation device, in order to stabilize the oscillation, the terminating resistor is connected to a quarter-wave open end for the resonance frequency f.sub.o or a spurious oscillation frequency f.sub.s, and as a result, the ground impedance of the terminating resistor is made zero at the resonance oscillation frequency f.sub.o or the spurious oscillation frequency f.sub.s. This will be explained later in detail.
In the above-mentioned prior art, however, the ground impedance of the terminating resistor is not zero even at a frequency slightly different from the resonance oscillation frequency f.sub.o or the spurious oscillation frequency f.sub.s. Therefore, it is impossible to completely stop spurious oscillations.